Short-sightedness linked to hard study

8th May 2012

Between 80 and 90% of school leavers in the major cities of China, Japan and South Korea are short-sighted, and researchers say this could be the result of too many hours of hard study.

The epidemic of short-sightedness sweeping across the East Asian region has been blamed in a recent review on too many hours spent indoors under artificial lighting, studying intensively in a hyper-competitive education system.

In a recent article in The Lancet, Australian experts are suggesting that such widespread myopia among young people in East Asia could be caused by the lifestyles expected of the region's schoolchildren and college students.

According to article author Ian Morgan of the Australian National University in Canberra, "intense" levels of education could be to blame for the problem, which is so severe that 10-20% of sufferers have "high" levels of myopia, which can lead to blindness.

Citing a number of recent studies that contradict received wisdom that myopia is inherited, Morgan cites a slew of recent studies that suggest short-sightedness relies far more on environmental factors than on genetic make-up.

"The rise in myopia prevalence in urban east Asia might therefore be plausibly associated with the increasing intensity of education," Morgan wrote.

He added that the East Asian countries with the highest educational performance were also the countries with the highest levels of short-sightedness.

A recent study, the Sydney Myopia Study, showed that children who read continuously or with the reading material close to their faces were more likely to be myopic.

The antidote appears to be to spend more time outdoors, according to a separate study.

Morgan said that total time spent outdoors seemed to yield a protective effect, as opposed to taking part in any particular activity.

It is possible that eyesight is protected in this way because exposure to sunlight stimulates the release of the neurotransmitter dopamine in the retina.

Previous studies in primates have shown that exposure to bright light reduces the risk of short-sightedness.

While experts conceded that a person's genes also play a role in myopia risk, they are not yet sure how a large number of small-impact genes contributes to the problem, nor how the environment interacts with genes to affect a person's risk of myopia.

They concluded that even if successful prevention were possible, East Asia will still be faced with the possibility of large numbers of adults developing high levels of myopia for at least the next century.

They called for further research to investigate ways of treating myopia, and to understand the natural history of pathological myopia.